He studied 1969-1973 math, physics and philosophy at the University of Tübingen and received his PhD 1976 from the University of Mainz. His PhD advisor was Judita Cofman. From 1982-1985 he was an associate professor at the University of Mainz and from 1985-1988 he worked for a research department of the Siemens AG. Since 1988 he is a tenured professor for geometry and discrete mathematics at the University of Giessen. He became a well-known popularizer of mathematics in Germany by authoring several books in the field of popular science and recreational math and for founding Germany's first math museum, the Mathematikum. He received several awards for his contributions to popularizing mathematics. He has a math column in the German popular science magazin Bild der Wissenschaft and moderates a popular math series for the TV-Channel BR- \alpha (educational TV).

regular

• Cryptology. Spectrum
• with Lynn Batten: The Theory of finite linear Spaces. Cambridge University Press
• with Uta Rosenbaum: Projective Geometry: From Foundations to Applications. Cambridge University Press
• Lineare Algebra. Vieweg, Wiesbaden 1994, 6. ergänzte Aufl. 2003, ISBN 3-528-56508-X
• Einführung in die endliche Geometrie I. Blockpläne. B.I. Wissenschaftsverlag
• Einführung in die endliche Geometrie II. Projektive Räume. B.I. Wissenschaftsverlag
• Diskrete Mathematik für Einsteiger. Vieweg
• with Bernhard Petri: Der goldene Schnitt. 2. Auflage. Spektrum, Heidelberg, Berlin, Oxford 1996, ISBN 3-86025-404-9

popular science

• Pasta all´infinito. Meine italienische Reise in die Mathematik. 2. Auflage. C.H. Beck, München 2000, ISBN 3-406-45404-6
• Luftschlösser und Hirngespinste. Vieweg, Braunschweig und Wiesbaden 1986
• Geheimsprachen. Geschichte und Techniken. 3. Auflage. C.H. Beck, München 2002, ISBN 3-406-49046-8
• In Mathe war ich immer schlecht. 3. Auflage. Vieweg, Braunschweig und Wiesbaden 2001, ISBN 3-528-26783-6
• Christian und die Zahlenkünstler. Eine Reise in die wundersame Welt der Mathematik. C.H. Beck, München 2005, ISBN 3-406-52708-6